From: Johannes Berg <johannes@sipsolutions.net>
To: Randy Dunlap <rdunlap@infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-wireless <linux-wireless@vger.kernel.org>,
linuxwifi@intel.com
Subject: Re: 4.19-rc[23] iwlwifi: BUG in swiotlb
Date: Tue, 11 Sep 2018 09:32:57 +0200 [thread overview]
Message-ID: <1536651177.3224.106.camel@sipsolutions.net> (raw)
In-Reply-To: <0c5e53e5-2afa-8d38-0b48-272c670c4bc5@infradead.org> (sfid-20180911_041837_063528_262C06DC)
On Mon, 2018-09-10 at 19:17 -0700, Randy Dunlap wrote:
> Hi,
>
> Any ideas?
Hmm. Is this new?
> 2018-09-10T18:47:54.532837-07:00 dragon kernel: [ 31.472371] kernel BUG at ../kernel/dma/swiotlb.c:521!
nslots = ALIGN(size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
[...]
BUG_ON(!nslots)
> 2018-09-10T18:47:54.613655-07:00 dragon kernel: [ 31.490325] swiotlb_alloc+0x88/0x170
> 2018-09-10T18:47:54.613656-07:00 dragon kernel: [ 31.490329] ? __kmalloc+0x1cc/0x200
> 2018-09-10T18:47:54.613657-07:00 dragon kernel: [ 31.491652] iwl_pcie_txq_alloc+0x1d4/0x3b0 [iwlwifi]
There are two calls to dma_alloc_coherent() here, should those even hit
swiotlb? The sizes of those should be
* 256 x 128 (32k)
* 32 x 256 (8k) [TFH, unlikely to be the case here]
* 256 x 256 (65k) [TFH]
* 32 x 64 (2k)
* 256 x 64 (16k)
IO_TLB_SHIFT is 11, so we get 2k alignment, so even the smallest size
(32*64) should result in nslots being 1?
In fact, unless the driver passed *ZERO* as the size, this should never
happen (hence the BUG_ON), since ALIGN() would take care of rounding up
any smaller allocation here.
Presumably you can reproduce this pretty easily (and I don't know what
specific model of NIC you have etc.), so perhaps you can do something
like this?
https://p.sipsolutions.net/aa0dccd7a60fe176.txt
johannes
next prev parent reply other threads:[~2018-09-11 12:31 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-11 2:17 4.19-rc[23] iwlwifi: BUG in swiotlb Randy Dunlap
2018-09-11 7:32 ` Johannes Berg [this message]
2018-09-11 20:57 ` Randy Dunlap
2018-09-11 21:02 ` Johannes Berg
2018-09-16 9:34 ` Pavel Machek
2018-09-16 9:41 ` Pavel Machek
2018-09-16 9:55 ` Pavel Machek
2018-09-16 9:59 ` [PATCH] fix iwlwifi on old cards in v4.19 was " Pavel Machek
2018-09-16 10:12 ` [linuxwifi] " Grumbach, Emmanuel
2018-09-16 10:14 ` Grumbach, Emmanuel
2018-09-16 11:06 ` Pavel Machek
2018-10-07 0:44 ` Randy Dunlap
2018-10-07 0:56 ` Randy Dunlap
2018-09-16 22:27 ` Randy Dunlap
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